While cleaning out my study, I found my Garmin Edge 305 GPS sitting in the back of a desk drawer. The poor, poor neglected device hasn’t had any fitness loving in the last year because its battery was unable to hold a charge more than an hour – down from >10 hours new. This is a limitation with Li-Ion batteries.
It’s well-beyond warranty. For a flat-rate repair fee of $79, Garmin will swap it out with a refurbished unit. That’s 35% of what the unit goes for new, so I was wondering what would be involved in doing it myself. A quick cruise down the Intertubes showed MTB Guru has already made a great tutorial on the mechanics. Assuming one has the tools, it costs less than $10.
Supplies:
- A 3.7V Lithium-Ion battery – this one will fit, but it has slightly less capacity (800mAh) than the original one (850mAh). I used a LG 8350 cell phone battery (1000mAh): $6 on eBay.
- Solder – A small tube of 60/40 solder is $1.50 at Fry’s.
- Rubber cement – you can use the little tube that comes with the ye-old-style bicycle tube patch kits. (I have yet to master the glueless patches. It’s quite possible these just suck.)
- Dab of super glue.
- (Optional) Flame decals, leftover from another project.
Tools:
- A soldering iron – This was a great excuse to break open the fancy pants one I received as a gift. A cheap $6 hobby model will also do.
- A third hand tool or an assistant who trusts your handling of a pointy, metal-liquifying tool near their personage. The third-hand tool is $3 at Harbor Freight Tools. The assistant: priceless.
- A stack of phone books or 160 ICML papers to review. (Ted’s CS Ethics text books may also be substituted.)
- Mini Philips screwdriver. This is sometimes known as a “jeweler’s screwdriver.” I don’t wear jewelry, so I’ll just have to take Their Word on that.
- (Optional) Wire strippers. You can also use scissors or a knife.
- (Optional) Dremel tool. This will make a neater spot for the larger battery.
- (Optional) Single-edge razor blade. Oh, so useful!
Step 1: Preheat oven to 350F. Ooops, wrong recipe.
Step 1a: Consider your options. Garmin will swap out the unit for a flat-rate repair fee of $79. If you have other problems with the unit or are uncomfortable with letting the magic smoke out of the GPS, this might be a better option. Otherwise…
| Step 2: Congratulations, your warranty is no more voided than it was before. Wedge a fingernail in the seam between the buttons and the base. (In the photo below, the Edge is upside-down.) You’ll need to work around the case twice to break the rubber cement seal.Breaking the seal!
The photo on the right shows the expanding gap. You’re ready to crack (open) the case! You use a fingernail — not a knife or a machete — to avoid damaging the case. |
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| Step 3: Let the magic smoke out! Set the unit down on its face and g-e-n-t-l-y pry off its back. If there isn’t a bright, explosive flash, you’ve done it right.
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| Step 4: That wasn’t so hard, was it? Okay, we’re going to be doing most of our work on the part I’m holding. However, before we start, some things I want to point out.  |
See this switches? They’re fragile. Bend them you will not! Unfortunately, once you break open the unit, you’ll have a hard time with these making the necessary contact to the back of the case. Not to worry, we’ll address that later. |
| Step 5: If you gently tap this on a soft surface, the main motherboard will pop out. This would be a good opportunity to wash the dust off everything.  |
Step 36: Okay, back to the base. You’ll notice that the new battery is slightly larger than the old one. This is a small price to pay for 25% more use per charge. |
Step 57: The old battery is held in place by double-sided tape. Pry it out. |
| Step 78: Remove the little piece of black electrical tape on top of the battery.Hold the red wire near the battery. Wiggle it until the wire breaks from the solder point. Repeat this with the black wire.
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| Step 100: With the battery out of the way, we need to do a tabectomy so the new battery will fit. There are three tabs on the back – remove them.If you have a Dremel tool, just grind them off. Otherwise, grip them with a pair of pliers and bend until they break off.
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| Step 111: Using the wire strippers (or scissors), peel off 1/4″ of insulation from the end of each wire. Twist the end of each wire so the little strands are tightly wound. This will make it easier to solder.Warm up the soldering iron.Place the base and battery on your hands-free tool like so:
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| Step 128: Solder the red wire to the metal strip with the “+” sign. The black wire will be soldered to the metal strip with the “-” sign.Mr. Huber’s head would spin at my soldering skills, but as long as the wire’s secure and it’s not shorting anything out, we can call this “good enough.”
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| Step 13732: After everything cools down, apply a piece of electrical tape on top of the soldered wires. I routed the wires to behind the battery and applied another piece of tape there, too.The purpose of the tape is to keep the wires from wiggling and breaking off.
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| Step 14123444: Plug in the USB cord to the base for 10 minutes. This will give the battery a small charge. Now, take the circuit board, and press it against the base so the flimsy metal contacts contact.Press the top-left button (power on). If you see a display, your wiring is fine. If not, look for a bad solder joint or short.
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| Step 15 gazillion: The little connectors are flimsy and, now that we’ve taken it apart, are likely to wiggle on bumpy roads. So we don’t have the GPS shut off during a ride, we’ll do some minor augmentation of the contact board.From a thick sheet of paper (I used the cardboard sheath for the single edged razor blads), cut four 1/8″ by 1/4″ strips.
Loosen the two screws about two or three turns. Pry the board up with your finger. On each side, insert a two strips. You want them to be flush with the edge of the board. Tighten the screws – it should only take 1 turn.
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Step 16 billion: Okay, now put the display board back into the front half. Put both halves of the GPS together and power on again. We’re just verifying we didn’t misalign the board. |
| Step 17 skiddoo: Now it’s time to glue this bad boy back together. Apply four dabs of super glue at the top of the base – see below.Quickly, add a seam of rubber cement around the perimeter. The super glue is to keep the case from jiggling apart, the rubber cement will provide a better seal while also making it possible to do this again in two years.
Press the unit together!
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| If you don’t have access to 160 ICML papers, or Ted’s CS Ethics text book, use a stack of phone books. Dang, I get a lot of phone books… Or, better yet, if you have two ratchet clamps, use those. The glue should dry in about 20 minutes.  |
Pop the USB plug in and fully charge the unit! Apply flame decals. It’s immediately faster! |